. Diseases of plants induced by cryptogamic parasites; introduction to the study of pathogenic Fungi, slime-Fungi, bacteria, & Algae. Plant diseases; Parasitic plants; Fungi. 364 UREUINEAK. direction ; their sori form dark spots which break out from beneath the epidermis. The yeHow uredospores have a coat beset with fine spines, and are given off from sori which may or may not be enclosed in a peridium. The sori of the aecidium-stage have no peridium, and are known under the generic name of Caeoma; they frequently occur on other hosts than tliose of the teleutospores. Pycnidia are produced
. Diseases of plants induced by cryptogamic parasites; introduction to the study of pathogenic Fungi, slime-Fungi, bacteria, & Algae. Plant diseases; Parasitic plants; Fungi. 364 UREUINEAK. direction ; their sori form dark spots which break out from beneath the epidermis. The yeHow uredospores have a coat beset with fine spines, and are given off from sori which may or may not be enclosed in a peridium. The sori of the aecidium-stage have no peridium, and are known under the generic name of Caeoma; they frequently occur on other hosts than tliose of the teleutospores. Pycnidia are produced in little yellow ]tatches. Melampsora tremulae Tul. (Britain). The sori of uredo- spores appear as little yellow protuberances on leaves or young shoots of Populus tremida. The dark-brown patches of teleuto- spores appear later on the under epidermis, and where they. Fio. 196.—Caeoma 'pinitorquum. Section showing four pycnidia, from one of which (xj>) numerous conidia are being discharged. Caioma-pMches are developing beneath the cortical layer, as yet unbroken. (After R. Hartig.) occur in large numbers, an early fall of the leaf may result. The teleutospores hibernate in dead leaves on the ground. In spring the sporidia germinate and infect young shoots of Pinus sylvcstris, producing the disease known as Caeoma jnnitorquMm} This disease attacks pine-seedlings, appearing generally on the needles. It is most frequent in plantations from one to ten years old, rarer in those of ten to thirty years, and not as yet observed in older. Pinus sylvcstris is most commonly attacked, but it has also been observed on Pinus montana in Jiitland. After formation of the Caeoma--psitches, the young thin shoots generally die off, but thicker ones become twisted at the place attacked, whence the name " pine-twister " commonly given to this disease. If the leading shoot be attacked, the seedlings may succumb altogether. The disease develops rapidly, ' R. Hartig, mchfi'je Krankhcitcn
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Keywords: ., bookcentury1800, bookdecade1890, bookpublisherl, booksubjectfungi
